Some people think of "alternative currencies" as wonderful solutions to economic problems. But obviously, no currency can have any significant impact without becoming legal tender.
So what would happen if a country actually adopted an "alternative currency" as legal tender? Well, unless you're in El Salvador, you're in luck: it's already been tried.
December 2021 Update: There's even better news (that is, unless you still haven't fled El Salvador). If you were waiting for the occasion to test your great idea of building a city next to a volcano, someone else might do the job for you.